Electric Machines with Reconfigurable Windings for Automotive Applications

The performance of electric machines for automotive applications is characterised by a high transient torque capability for low speed tractability and a large speed range of high energy conversion efficiency to achieve a desirable vehicle range. Inevitably, these conflicting requirements will introduce a compromise in the design process of electric machines and drives, generally resulting in heavier machines and overrated drive specifications. This paper discusses the principles of reconfigurable windings, explaining how altering winding connections directly influences key machine parameters like flux linkage, inductance, and resistance. It details the necessary switchgear for series-parallel winding reconfiguration, highlighting potential advantages such as enhanced fault tolerance and emergency braking capabilities. A prototype in-wheel motor with series-parallel reconfigurable windings, developed as part of the EM-TECH Horizon Europe project, is presented. Simulation results using the Artemis MW130 driving cycle demonstrate that an efficiency-optimized gear shifting strategy can achieve a 1.57% reduction in energy consumption and a speed range extension greater than 50% compared to a fixed winding configuration. This highlights the potential of reconfigurable windings to improve the range of Battery Electric and Hybrid Electric Vehicles (BEVs/HEVs) by reducing drive cycle losses across various speed regions.